1. Field of the Invention
Example embodiment of the present invention relate to a dynamic random access memory (DRAM) device and a method of manufacturing the same, and more particularly to an integrated DRAM device and a method of manufacturing the same.
2. Description of the Related Art
Conventionally, a unit cell of a DRAM device may include one pass transistor and one capacitor that may be electrically connected in series. A pass transistor may control the movement of electrons into and/or out of a device, thereby functioning as a switching element controlling whether electrons are accumulated in or charged from a capacitor. Data may be stored and/or erased in a DRAM device when electrons are accumulated into or charged from a capacitor.
A conventional pass transistor in a DRAM device may include a planar gate electrode. In a planar gate electrode, a channel length may decrease proportionally with a decrease of a line width of a gate electrode. Accordingly, when a design rule for a DRAM device is no more than about 100 nm, the DRAM device is frequently influenced by a short channel effect, which may generate an operation failure in the DRAM device.
A conventional DRAM device may further include a connection member for electrically connecting a pass transistor and a capacitor. Accordingly, an accurate aligning process is normally required when forming a connection member. Because of the accurate aligning process, obtaining an area of 4F2 (wherein, F indicates a critical dimension of the DRAM) for a DRAM is difficult.
A pass transistor in a conventional DRAM may be formed on a silicon substrate and/or a silicon layer grown by an epitaxial process (hereinafter, referred to as silicon epitaxial layer). Vertically stacking a pass transistor on a silicon substrate or silicon epitaxial layer may be difficult. Accordingly, vertically stacking a unit cell of a conventional DRAM on a substrate to form a multilayer structure is difficult.
For at least the above reasons, increasing an integration degree of conventional DRAM devices has been difficult.